1. Field of the Invention
The present invention relates to a workpiece transfer robot system in which a robot transfers a workpiece relative to a machine tool.
2. Description of the Related Art
A robot system for transferring, in particular, loading or unloading, a workpiece relative to a machine tool, which includes a robot composed of a traveling axis mechanism including a track member defining a traveling axis and a slider traveling along the track member, and a movable arm mechanism (i.e., a robot arm) mounted on the slider, is known. In a production line equipped with a robot, a workpiece is transferred to several locations, such as a workpiece support section inside a machine tool, a feed table on which a workpiece before being loaded into the machine tool is placed, a delivery table on which a workpiece unloaded from a machine tool after being processed by the machine tool is placed, etc. Thus, the robot composed of a traveling axis mechanism and a movable arm mechanism mounted thereon is provided between several transfer locations, so that it becomes possible to enlarge the working space of the movable arm mechanism in the longitudinal direction of the track member, while preventing the dimensions of the movable arm mechanism from increasing, and thus to readily or flexibly transfer the workpiece between the several transfer locations. Further, the robot including the traveling axis mechanism can relatively easily prevent the robot from interfering with the machine tool or other peripheral equipment in comparison with a robot including only a large-sized movable arm mechanism.
Japanese Unexamined Patent Publication (Kokai) No. 5-318249 (JP5-318249A) describes a system including a robot for transferring a workpiece relative to a main spindle of a machine tool or a provisional table, in which the robot is provided inside a housing of the machine tool. The robot includes an arm slidable along a guide rail formed on a beam, and a chuck for holding the workpiece is provided at the distal end of the arm.
Japanese Patent No. 3865703 (JP3865703B) describes an article transfer system in which a workpiece is fed to and delivered from a processing machine by a robot. The robot includes an arm movable along a track member put up or constructed over the front yard of the processing machine. The cover of the processing machine is provided at a front side thereof with an opening allowing the robot arm to access the interior space of the cover. The track member extends in a direction parallel to the front side wall of the cover of the processing machine.
Japanese Unexamined Utility Model Publication (Kokai) No. 6-33690 (JP6-33690U) describes a traverse robot including a robot hand traveling along a traverse rail. The robot hand moves in a vertical direction perpendicular to the extending direction of the traverse rail.
The machine tool is generally configured so that an operator can access the interior space of the cover of the machine tool through the front opening of the cover and perform certain works, when it is necessary to change the type of workpiece or conduct maintenance on workpiece-processing tools attached to the machine tool. The operator's works include replacement, adjustment or inspection of a retention mechanism (such as a table, a chuck, a mold; hereinafter referred to as a workpiece support section) or a workpiece mount section, the replacement of the tools, the washing of mechanical portions, and so on. An operation panel may be provided on a front side of the machine tool.
In a configuration in which a robot arm enters through an opening formed in the cover of a machine tool into the interior space of the cover, it is reasonable to commonly use a front side opening provided for an operator's work as an entrance opening for the robot arm (see, e.g., JP3865703B). However, in this case, the robot arm is disposed at the front side opening of the machine tool during a time when the robot is operating, and therefore, the operator cannot approach the front side opening of the machine tool. Thus, inconvenience may occur in an operator's work that essentially does not need to stop the robot, such as a visual check of a workpiece processing state, or in an operator's work performed simultaneously with the operation of the robot, such as a check for the operation of the robot inside the cover. Further, if the robot arm is located in front of the front side opening of the machine tool when the robot is stopped for, e.g., a maintenance work of the machine tool, a space for allowing the operator to perform the work may be inconveniently narrowed.
In the system configuration described in JP3865703B, for example, an opening for operator's works may be formed in a side wall of the cover of the machine tool, which is different from the front side wall having the entrance opening for the robot arm. In this configuration, the above-described inconveniences in operator's works may be eliminated.
In a case where the above-described robot system is installed in facilities such as a factory, an exclusive pathway, through which an operator can safely pass, may be provided along the longitudinal direction of track member. In this configuration, various components of the robot system can be placed relatively closer to the pathway, and an operator thereby can easily access the respective components for, e.g., a maintenance work. Further, in a case where a plurality of robot systems are laid side-by-side with each other in, e.g., a factory, it is possible to efficiently use spaces for installing the respective robot systems, and thus to establish a reasonable layout, e.g., a parallel arrangement of a plurality of pathways.
In the above layout, if the opening for operator's works is formed in the side wall of the cover of the machine tool, which is different from the front side wall having the entrance opening for the robot arm, it is necessary for an operator to leave the pathway so as to move toward a working space, and thereby the working efficiency of the operator may be lowered. Further, in order to ensure the working space of the operator, the arrangement density of the machine tool and peripheral equipments may be reduced.
On the other hand, for example, the traverse robot described in JP6-33690U may be disposed above the machine tool and configured to shift the robot hand downward into the interior space of the cover through an opening formed in the top wall of the machine tool. In this configuration, it is necessary to locate the traverse rail at a sufficiently higher position above the machine tool. As a result, cost may be increased, and in some facilities such as a factory, it may be difficult to ensure the height for laying the traverse rail.
Further, in a case where the machine tool is configured so that a tool attached to the distal end of a vertically-disposed main spindle operates to process a workpiece immediately beneath the main spindle, it may be difficult, for the traverse robot including the robot hand shiftable in a vertical direction, to allow the robot hand to access the workpiece support section provided immediately beneath the main spindle. In this case, in order to make possible to load/unload the workpiece relative to the workpiece support section provided immediately beneath the main spindle, the additional equipment of a table retracting mechanism for laterally shifting a processing table as the workpiece support section may be required, or the efficiency of the transferring task may be lowered due to the table retracting operation.
Still further, in any of the above-described configurations, when the movable arm mechanism (i.e., the robot arm or the robot hand) is inserted into or pulled out from the interior space of the cover of the machine tool, it is required to shift the orientation of the movable arm mechanism on the track member (i.e., the guide rail or the traverse rail) to a retracted orientation capable of eliminating interference with the mechanical section or cover of the machine tool. The shifting of the orientation of the movable arm mechanism to the retracted orientation may increase a time required for the loading/unloading of the workpiece, and thus may deteriorate the efficiency of the transferring task.